Back to front thinking
Porsche, Toyota and Audi had already embellished the WEC with fascinating technological diversity… and then Nissan unveiled its radical new front-wheel-drive Le Mans challenger
Writer Gary Watkins
Nissan grabbed the pre-season World Endurance Championship headlines – and gathered some more when it withdrew its radical GT-R LM NISMO from the first two rounds at Silverstone and Spa. The first tranche was undoubtedly positive, the second was clearly always going to be negative. So what reaction will the manufacturer receive when the front-engined, front-wheel-drive contender makes its belated race debut in the Le Mans 24 Hours?
If the Japanese manufacturer can hit its stated goals, then it has a fighting chance of more positive headlines. And those goals are now befitting of a manufacturer that has not only opted for such an unusual concept, but is also returning to the pinnacle of sports car racing after an absence that stretches back to 1999.
The outlandish claims that Nissan was going to win Le Mans on its comeback, made at the project launch last May, have disappeared along with the man who made them, former vice-president and now Aston Martin boss Andy Palmer. They were tempered at the time by the marque’s global motor sport boss, Darren Cox. And a year on, his aspirations are much more modest: he wants the best of the GT-R LMs to qualify among its factory rivals from Audi, Toyota and Porsche, and then have at least one of its three entries still running at the finish.
“People seemed to have forgotten that Toyota missed the first two races when it returned in 2012,” says Cox, who is calling 2015 a learning year. “We are in the normal process of developing a car and ours is a little bit different to everyone else’s, which is why it is taking time.”
That development hasn’t been entirely straightforward. Nissan was forced to miss Silverstone because the car was not homologated in time after twice failing its crash test. It has also had to modify the monocoque design for a second reason. The rule makers insisted that a kind of bellhousing between the chassis and engine, which could originally be removed along with the twin Torotrak energy-storage flywheels that sit underneath the driver’s legs, be bonded in place. It opted then to miss Spa as well in order to rack up the testing miles and focus on Le Mans, the race for which the GT-R LM was designed.
At the time of its original planned debut at Silverstone in mid-April, the car had completed just 3800km of running across a variety of circuits in the USA, including the Circuit of the Americas in Austin, Sebring and, most recently, Chevrolet’s test track at its Bowling Green facility in Kentucky, just down the road from the project’s Indianapolis base. Ben Bowlby, both the architect of the car in his role as technical director and team principal of Nissan Motorsports, reveals that testing up to that point had been largely focused on getting the car’s fully mechanical hybrid system built by Torotrak in the UK to work correctly. Only after Silverstone were the first endurance runs planned, also at Bowling Green.
The testing has all been undertaken with the regenerated power from the hybrid system returning to the front wheels. The car was conceived to deploy the retrieved energy at the rear wheels, but this system was abandoned in the interest of weight saving, according to Bowlby. Putting the power of the car’s twin-turbo 3-litre V6 and the recovered energy – which together add up to 1250bhp, according to Nissan – through the front axle has inevitable consequences.
“If you are recovering eight megajoules [the amount Nissan was targeting] from the front axle, the size of the brakes is different from when you are only taking 4MJ, for example,” says Bowlby, who wouldn’t confirm that the car will run in the hybrid sub-class that allows for 2MJ to be deployed over the Le Mans lap. “It is true that we are running 18in wheels instead of 16in wheels, because we had to fit brakes that a 16in wheel wouldn’t accommodate. That has had a huge knock-on effect on elements of the car.”
Tyre wear would appear to be another one. Nissan and its drivers claim to have made major advances in this respect during early April.
“Up to the Sebring test [in early March] we were struggling to get the laps, but we have made a big step,” says Marc Gené, who will share the no23 Nissan with Max Chilton and Jann Mardenborough. “Now we are able to do long runs, which we couldn’t before.”
Olivier Pla, who drives the other regular entry together with Harry Tincknell and Michael Krumm at Le Mans, suggests the car is already light on its toes. “We were very surprised about how the car looks after its tyres,” he says. “Over two stints the car was very consistent, which is quite promising, and there is more work to do with Michelin.”
Bowlby remains optimistic for Le Mans: “Our engine is a beast, so you might say that we are playing to our strengths by going up in fuel allocation and down in energy recovery.”
Yet he still reckons that it could be 12 months before his unconventional concept shows its true colours. “We have designed the whole car around a hybrid system that has to get to 8MJ,” he says. “I think we’ll be in a lot better shape in 2016.”
How it works
Designer Ben Bowlby on why he overturned 50 years of thinking
Get Ben Bowlby to explain the concept behind the GT-R LM, and he’ll have you believing by the end. He presents his theory in a simple, elegant and even charming way. It runs along the lines of, “If you do this, why not do that?” He makes it sound logical. Obvious, even.
The starting point, he explains, is the aerodynamic limitation imposed by the rule book at the rear of the car.
“If you begin to think about how you could differentiate yourself aerodynamically when the rear diffuser is so strictly controlled and the rear wing has to fit within a tight box, you basically realise that you would have to spend a fortune in detail work and fine tuning,” he says. “It is much easier to find the downforce to make the difference at the front.”
That isn’t possible with a conventional car because, says Bowlby, “The footbox chassis rules cause the monocoque to be quite wide.” The tub on a conventional rear-engined design means that the airflow under or through the car restricts aerodynamic gain. He adds: “We thought that if we moved the engine forward and used a vee configuration that is narrow at the bottom and then position the engine carefully, then we can make a very accommodating and effective shape aerodynamically to maximise the flow under the splitter around a nice teardrop shape and out the back of the car.”
It is, says Bowlby, an “integrated approach”. Moving the engine to the front allows the front-weight distribution to be brought forward to match the shift in aero balance over a conventional car in the same direction.
“It all started to piece together quite nicely and was sufficient for us to say, ‘You know what, I think this could work’,” he says. “It was no slam-dunk, but we started doing our simulations and thought it was a way to be competitive at the same time as being interesting and different.”
The lateral thinking didn’t stop there. Bowlby and his team could still have opted for rear-drive traction, but a propshaft and differential would have added weight.
“Making weight is extremely difficult with a big, powerful hybrid,” says Bowlby. “It is probably the biggest challenge that the manufacturers face in designing and building these cars. So we said, ‘OK, we will use our relatively low-powered internal combustion engine to drive the front wheels and boost acceleration by driving the rears’.”
The forward bias of the aero forces and weight distribution will also aid energy recovery from the GT-R LM’s front-axle kinetic system. “You want to recover from the front where you have the downforce and weight,” says Bowlby. “That way you have a better chance of recovering a lot of energy.”
The concept of the GT-R is to recover from the front and deploy to the rear to take advantage of the weight transfer under acceleration. “That seemed like an intelligent thing to do,” says Bowlby. “And then you look at the duty cycle of the rears and the weight and aero distribution, and you think that it wouldn’t be too bad to go for a smaller rear tyre.”
That explains the GT-R LM’s nine-inch rear wheels, five inches narrower than the 14 allowed, in the interests of drag reduction on a car that Bowlby makes no bones in admitting has been designed as a Le Mans special.
“If you can turn that wasted grip into aerodynamic efficiency, it isn’t such a bad compromise,” he says. “We are running at such high speeds for such long times at Le Mans that drag is very important. In the overall equation it looks like a decent trade-off.”